Various optical devices have been designed to align one optical system with another. An autocollimator is one such device.
The autocollimator, as shown in FIG. 1 (Prior Art), projects a highly collimated beam of light 10 at the optical device 12 to be aligned with respect to the autocollimator. The device 12 to be aligned is made to reflect light back towards the autocollimator and light from the beam source also is reflected directly to a view screen through beam splitter 13, each producing light spots on the view screen 15. The light reflected back will be deviated from the transmitted beam by twice the angle of misalignment (tilt). The light directed to the device 12, and reflected back into the autocollimator, travels through the telescope optics 14, e.g. the eyepiece and objective lenses, and is reflected by beam splitter 13 to the eyepiece or view screen 15. This means that an image of the received light appears as a spot.
Most autocollimators are designed in such a way as to show the incoming light as a spot on a reticle, the reticle having markings that indicate angular displacement. Furthermore, autocollimators are generally designed with costly very high precision diffraction limited optical elements. This is important because the autocollimator serves as a precision collimator to produce a highly parallel transmitted beam that can propagate as far as diffraction will allow. This enables the user to align devices separated by great distances. An example of such an autocollimator in the patent art is found in U.S. Pat. No. 3,836,258.
The purpose, of this invention (herein called an xe2x80x9cangle finderxe2x80x9d) is to develop a relatively simple instrument for aligning a device or devices which transmit (or use) as an alignment feature a collimated (e.g. laser) light beam. Such a device is equipped or includes an adjustable light transmitter such as a laser beam generator, and for purposes of alignment has the instrument of this invention, which is a totally passive instrument, attached to it. This instrument acts as a receiver of the beam of light and displays an indication of misalignment of the beam, and also aids in correcting same.